Programmable integrated circuit devices (ICs) are a well-known type of IC that can be programmed to perform specified logic functions. One type of programmable IC, the field programmable gate array (FPGA), typically includes an array of programmable tiles. These programmable tiles can include, for example, input/output blocks (IOBs), configurable logic blocks (CLBs), dedicated random access memory blocks (BRAM), multipliers, digital signal processing blocks (DSPs), processors, clock managers, delay lock loops (DLLs), and so forth.
Each programmable tile typically includes both programmable interconnect and programmable circuitry. The programmable interconnect typically includes a large number of interconnect lines of varying lengths interconnected by programmable interconnect points (PIPs). The programmable circuitry implements the logic of a user design using programmable elements that can include, for example, function generators, registers, arithmetic logic, and so forth.
The programmable interconnect and programmable circuitry are typically programmed by loading a stream of configuration data into internal configuration memory cells that define how the programmable elements are configured. The configuration data can be read from memory (e.g., from an external PROM) or written into the FPGA by an external device. The collective states of the individual memory cells then determine the function of the FPGA.
Another type of programmable IC is the complex programmable logic device, or CPLD. A CPLD includes two or more “function blocks” connected together and to input/output (I/O) resources by an interconnect switch matrix. Each function block of the CPLD includes a two-level AND/OR structure similar to those used in programmable logic arrays (PLAs) and programmable array logic (PAL) devices. In CPLDs, configuration data is typically stored on-chip in non-volatile memory. In some CPLDs, configuration data is stored on-chip in non-volatile memory, then downloaded to volatile memory as part of an initial configuration (programming) sequence.
For all of these programmable ICs, the functionality of the device is controlled by data bits provided to the device for that purpose. The data bits can be stored in volatile memory (e.g., static memory cells, as in FPGAs and some CPLDs), in non-volatile memory (e.g., FLASH memory, as in some CPLDs), or in any other type of memory cell.
Other programmable ICs are programmed by applying a processing layer, such as a metal layer, that programmably interconnects the various elements on the device. These programmable ICs are known as mask programmable devices. Programmable ICs can also be implemented in other ways, e.g., using fuse or antifuse technology. The phrase “programmable IC” can include, but is not limited to, the devices described herein and further can encompass devices that are only partially programmable. For example, one type of programmable IC includes a combination of hard-coded transistor circuitry and a programmable switch fabric that programmably interconnects the hard-coded transistor circuitry.
Hardware co-simulation refers to a process in which a portion of an electronic circuit is simulated within software executing in a host computing system and another portion of the electronic circuit is implemented using actual circuitry or hardware, e.g., within a programmable IC. The hardware portion of the electronic circuit within the programmable IC communicates with the software simulation within the host processing system, thereby allowing the circuit designer to test and simulate the entire electronic circuit.
Typically, the software portion of a hardware co-simulation executes within a high level modeling system (HLMS). The HLMS executes within the host processing system. The programmable IC communicates with the host processing system, and thus the software simulation, through a data link. With regard to the software portion of a hardware co-simulation, different portions of the circuit design, represented as software, execute within the HLMS in the host processing system. When the circuit design being simulated interacts with a processor, the processor also can be represented by, and execute as, software. Simulating the processor entirely within software, however, can be very time consuming. In such cases, it can be beneficial to implement the processor as hardware within the programmable IC. The processor disposed within the programmable IC can execute operational software as it normally would within the context of the circuit design being simulated. The processor then can communicate with the host processing system through the communication link during hardware co-simulation.